When doing date formatting, "yyyy" represents the day in which year, while "YYYY" represents the week in which
 * year (a concept introduced in JDK7). If a week is across two years, the returning "YYYY"represents the next year.
<p>Examples:</p>
<pre>
Negative example:
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    
Positive example:
        SimpleDateFormat format = new SimpleDateFormat("YYYY-mm-dd HH:mm:ss");
</pre>